French police patrol in the 'Jungle' migrants camp in Calais.PHILIPPE HUGUEN/AFP/Getty Images

Clashes broke out between migrants and police in Calais, with numerous officers reporting injuries, authorities have said. The overnight confrontation came as about 200 migrants moved to block traffic on a road leading to the French city's port in an attempt to raise their chances of stowing away on UK-bound lorries.

Police intervened to clean up the area as migrants threw objects on the pavement to slow down passing vehicles, the Calais prefecture said. The wife of a Romanian truck driver travelling with her husband was injured as a rock smashed their windscreen, BFMTV reported.

Security forces made use of tear gas, reportedly firing some 300 canisters to disperse migrants who were backed by activists from the No Borders group. Sixteen policemen were injured by stones hurled at them during the prolonged scuffles that took place meters away from makeshift migrant camps, known as The Jungle.

"It's the first time it got this violent," Gilles Debove, the head of a local police union, told Le Figaro. "We are worried, if one day there is a riot in a camp it will be madness." There were no immediate reports on the number of migrants wounded.

The incident came as tensions were rising in the camps, currently housing a record 6,000 people in the wake of security crackdown, according to charity workers. Controls on access to the port and Eurotunnel have made it significantly harder for migrants to cross to Britain and police have become "more and more aggressive" Maya Konforti, from the humanitarian group L'Auberge des Migrants, told IBTimes UK.

She pointed to a video showing security forces firing tear gas into a camp during a confrontation last week similar to that of 9 November.

Charities have also lamented the fact authorities have restricted their access to the camps, requiring entering vehicles to pre-register and that workers present personal identification. Konforti claimed activists bringing food and other commodities to the camps have been fined for illegal parking.

Already in January Human Rights Watch published a damning report accusing police of using excessive violence against migrants, an allegation French authorities have denied.

"Everything is being made to discourage people from remaining here," Konforti said, adding the situation in the camps was at its worse in 15 years. More than 750,000 asylum-seekers fleeing poverty and war have reached European shores in 2015, according to the UN.